Biology The Nematomorpha is a small phylum of aquatic worms with about 200 species worldwide. Their free-living adults are long and slender worms ranging from a few centimetres to about a metre in length. They occur mostly in fresh-water habitats (Order Gordioidea) with only a few species described from marine waters (order Nectonematoidea). The larval and juvenile stages are endoparasitic in aquatic or waterside arthropods, or in marine decapod crustaceans. [details]

Taxonomic remark Once recorded as a class under Cephalorhyncha [details]